Chronic allograft rejection is the leading cause of renal and cardiac allograft failure. The long term goal of this core is to assist investigators in acquiring the experimental data necessary for the successful investigation of this disease process. In this program project the murine heterotopic heart allograft model will be extensively utilized as an experimental tool for the investigation of chronic rejection; however, meaningful studies with this model will require the use of standardized tissue sections, special stains, and quantitative morphometric measurements. Therefore, the short term goals of the Histopathology and Morphometrics Core (9002) are to provide a centralized and standardized histology, immunohistochemistry, and automated morphometric analysis service for all projects. As a central core service it will guarantee a high level of uniformity, consistency and quality that will facilitate comparison of experimental results between the five program projects. The Specific Aims are to (I) provide a central histology service for all projects that will paraffin embed formalin-fixed tissues and provide stained tissue sections, (II) provide a central immunohistochemistry service for the detection of antigens within frozen or fixed tissues, and (III) provide an automated image analysis and morphometrics service that will provide consistent and uniform measurements of transplant vascular sclerosis in murine heterotopic heart transplants. The core will be located in The Ohio State University Hospitals and utilize the pre-existing Department of Pathology laboratories.